1. Field of the Invention
The present invention relates to a magneto-optical recording and reproduction device usable in a magneto-optical disk apparatus such as, for example, a mini disk apparatus.
2. Description of the Related Art
FIG. 12 shows a conventional magneto-optical recording and reproduction device 400 used in a magneto-optical disk apparatus such as a mini disk (hereinafter, referred to as an MD) apparatus or the like. A magneto-optical disk 12 includes a magneto-optical recording medium 12a and a transparent substrate 12b. 
The magneto-optical recording and reproduction device 400 includes an optical pickup housing 7 accommodating an optical pickup 17 for emitting a laser beam 4, a magnetic head 16 used for magnetic field modulation recording, a slidable member 3 (magnetic head slider), and a suspension 8 for pressing the slidable member 3 against the magneto-optical disk 12 with a constant load.
The optical pickup 17 includes an objective lens 5 for focusing the laser beam 4 which optically reproduces information from the magneto-optical disk 12 and which is used to raise the temperature of the magneto-optical recording medium 12a of the magneto-optical disk 12 when recording information to or erasing information from the magneto-optical disk 12, or when performing recording and erasing at the same time. The optical pickup 17 also includes a photodetector 6, and an actuator 18 for driving the objective lens 5 in a focusing direction or a radial direction of the magneto-optical disk 12 to adjust the position of the objective lens 5.
The magnetic head 16 includes a magnetic core 1 formed of a magnetic material such as Mnxe2x80x94Zn ferrite or the like, and a coil 2. The magnetic head 16 applies a magnetic field to a portion of the magneto-optical recording medium 12a which has had its temperature raised as described above by the laser beam 4.
The magneto-optical recording and reproduction device 400 further includes a magnetic head connection arm 9 for connecting the suspension 8 and the optical pickup housing 7 to each other, a guide shaft 10 which is a moving mechanism for moving the optical pickup housing 7 in a radial direction of the magneto-optical disk 12, and a subguide 11 for supporting the optical pickup housing 7. The magneto-optical recording and reproduction device 400 is incorporated into a chassis 14.
During an information recording or reproduction operation of the magneto-optical recording and reproduction device 400, a recording media surface of the magneto-optical disk 12 moves up and down in accompaniment with rotations of the magneto-optical disk 12. The magneto-optical recording and reproduction device 400 is structured to, during the information recording or reproduction operation, cause the actuator 18 to move the objective lens 5 up and down so as to follow the up-and-down movement of the recording media surface, so that the laser beam 4 is continuously focused on the recording media surface in a satisfactory manner.
During the information recording operation, the magnetic head 16 is on the recording media surface of the magneto-optical disk 12. For starting the information reproduction operation, the magnetic head 16 is lifted up from the recording media surface of the magneto-optical disk 12. Such an up-and-down movement of the magnetic head 16 is performed in order to extend the life of the magneto-optical disk 12 and the magnetic head 16 and reduce power consumption at a spindle (not shown) for rotating the magneto-optical disk 12. The magnetic head 16 is lifted up and lowered by, for example, a rotation mechanism 13, which is a hinge mechanism attached to the magnetic head connection arm 9, using a lifting plate (not shown) or the like. Currently, this structure is commonly used in magneto-optical recording and reproduction devices using a magnetic head.
In recent years, the size and weight of a magneto-optical disk apparatus have been reduced. For example, a disk used in an MD apparatus has a diameter which is as small as 64 mm. Techniques for reducing the size and the thickness of a magneto-optical recording and reproduction device have been actively developed to fit the device to the size of the disk. Furthermore, the magnetic field generation region in the magnetic head 16 for magneto-optical recording has been reduced due to the improvement in the recording density and data transmission rate. Therefore, extremely high level positioning and servo techniques of the optical pickup 17 are required.
When the size and the thickness of a magneto-optical disk apparatus are reduced, the weight of a device for driving the magneto-optical disk apparatus is also reduced, thus increasing the magnitude of vibration transmitted to a disk mounted on the magneto-optical disk apparatus. For example, referring to FIG. 12, the actuator 18 moves the objective lens 5 so as to follow the up-and-down movement of the magneto-optical disk 12. As a result, the actuator 18 vibrates, and the vibration of the actuator 18 is conveyed to the magnetic head connection arm 9. Since the vibration of the magnetic head connection arm 9 is transmitted to the magneto-optical disk 12, the magneto-optical disk 12 vibrates strongly. This causes a disturbance or a focus error in a focus servo system. The disturbance generated in the focus servo system can cause an adverse influence on the recording and reproducing characteristic of the magneto-optical recording and reproduction device. In the worst case, a recording and reproduction operation becomes impossible because the servo mechanism cannot provide sufficient control of the optical pickup 17 and the objective lens 5.
The data transmission rate during the recording and reproduction operation is required to be as high as possible. In order to obtain a higher speed than conventionally possible, inductance of the magnetic head 16 should be reduced. Such a reduction in inductance decreases the size of a magnetic pole of the magnetic head 16, which reduces the magnetic field generation region. Therefore, the position of the magnetic pole with respect to a laser spot on the magneto-optical disk 12 irradiated with the laser beam 4 is required to be more precise.
When reproducing the information stored on the magneto-optical disk 12 or taking out the magneto-optical disk 12 from the magneto-optical apparatus 400, the magnetic head 16 generally has to be significantly lifted up from the recording media surface of the magneto-optical disk 12. As shown in FIG. 12, the rotation mechanism 13, such as a hinge mechanism or the like, is used to lift up the magnetic head 16 from the recording media surface of the magneto-optical disk 12. Naturally, the hinge mechanism has some play. Therefore, the position of the magnetic pole with respect to the laser spot moves by a magnitude of this play. When this movement of the position is excessively large, the laser spot and the position of the magnetic pole are displaced from each other, resulting in the recording operation being impossible in the worst case.
According to one aspect of the invention, a magneto-optical recording and reproduction device includes an optical pickup for irradiating a magneto-optical disk with a laser beam for performing at least one of information recording to a magneto-optical disk, information reproduction from the magneto-optical disk, and information erasure from the magneto-optical disk; a magnetic head for providing a magnetic field to a position of the magneto-optical disk irradiated with the laser beam for performing at least one of the information recording and the information erasure, the magnetic head being located opposite to the optical pickup with respect to the magneto-optical disk where the magneto-optical disk is mounted on the magneto-optical recording and reproduction device; a housing for accommodating the optical pickup; a guide shaft for moving the housing; a suspension for supporting the magnetic head; and an arm for connecting the suspension and the housing. The guide shaft is on a straight line extending in a direction perpendicular to a plane of the magneto-optical disk from the center of gravity of a combination of at least the arm, the magnetic head and the suspension, so as to suppress a vibration of the arm, with the guide shaft being a fulcrum of the vibration.
In one embodiment of the invention, the magneto-optical recording and reproduction device further includes a rotation mechanism for lifting up and lowering the magnetic head, the rotation mechanism being attached to the arm, wherein the guide shaft acts as a rotation shaft of the rotation mechanism.
In one embodiment of the invention, the housing and the arm are integral with each other.
In one embodiment of the invention, the information erasure and the information recording are allowed to be performed simultaneously.
According to another aspect of the invention, a magneto-optical recording and reproduction device includes an optical pickup for irradiating a magneto-optical disk with a laser beam for performing at least one of information recording to a magneto-optical disk, information reproduction from the magneto-optical disk, and information erasure from the magneto-optical disk; a magnetic head for providing a magnetic field to a position of the magneto-optical disk irradiated with the laser beam for performing at least one of the information recording and the information erasure, the magnetic head being located opposite to the optical pickup with respect to the magneto-optical disk where the magneto-optical disk is mounted on the magneto-optical recording and reproduction device; a housing for accommodating the optical pickup; a guide shaft for moving the housing; a suspension for supporting the magnetic head; and a rotation mechanism for lifting up and lowering the magnetic head. The guide shaft acts as a rotation shaft of the rotation mechanism.
In one embodiment of the invention, the guide shaft is provided on the same plane as the magneto-optical disk or on the same side as the magnetic head with respect to the magneto-optical disk.
According to the present invention, a guide shaft for moving an optical pickup housing is on a straight line extending in a direction perpendicular to a plane of the magneto-optical disk from the center of gravity of a combination of at least a magnetic head connection arm, a magnetic head and a suspension. Due to such a structure, the up-and-down vibration of the magnetic head connection arm, with the guide shaft being a fulcrum of the vibration, which vibration causes a magneto-optical disk to vibrate, is suppressed. Therefore, a vibration component transmitted from the magnetic head connection head and the suspension to the magneto-optical disk can be suppressed.
It is preferable that the guide shaft be as close as possible to the center of gravity of the magnetic head connection arm in order to suppress the amplitude of the vibration of the magnetic head connection arm. Since the magnetic head connection arm extends substantially in a vertical direction from the magneto-optical recording and reproduction device. Therefore, the center of gravity of a combination of the magnetic head connection arm, the magnetic head and the suspension is in the vicinity of the magnetic head connection arm, and so the weight of the magnetic head connection arm is loaded on a connection portion of the housing with the magnetic head connection arm or the vicinity thereof.
In one embodiment of the invention, the guide shaft for moving the optical pickup housing also acts as a rotation shaft for a rotation mechanism for lifting up or lowering the magnetic head with respect to the magneto-optical disk. Such a structure is preferable since the precision in the position of the laser spot on the magneto-optical disk irradiated with a laser beam with respect to the magnetic field generation region of the magnetic head is improved. The size of the magnetic pole can be reduced to increase the frequency used for information recording, or the amount of heat generated can be reduced.
The vibration caused by the driving of an actuator is transmitted via the magnetic head connection arm to the magneto-optical disk and thus widely vibrates the magneto-optical disk. This vibration generally has a significant adverse influence on the servo characteristics both in a focusing direction and a radial direction. According to the present invention, the distance between the guide shaft and the magnetic head connection arm can be approximately zero. Therefore, the up-and-down vibration of the magnetic head connection arm can be sufficiently suppressed, and especially the servo characteristics in a focusing direction can be stabilized. Since the guide shaft also acts as the rotation shaft for the rotation mechanism, the number of components is decreased and the production cost is reduced.
In another embodiment of the invention, the guide shaft is located on substantially the same plane as the magneto-optical disk or on the same side as the magnetic head with respect to the magneto-optical disk. Due to such a structure, the distance in the height direction between the guide shaft and the magnetic pole (recording position) of the magnetic head can be shorter. Therefore, the precision of the position of the magnetic pole with respect to the laser spot on the magneto-optical disk irradiated with a laser beam is improved.
In a structure using a general shaft for moving the optical pickup housing, the guide shaft and a portion of the housing receiving the guide shaft need to have a clearance therebetween. Without the clearance, the guide shaft does not act as a guide shaft. Due to the clearance, the magnetic head (more precisely, the magnetic pole) vibrates with a certain amplitude with respect to the laser spot on the magneto-optical disk. This amplitude of vibration significantly depends on the distance between the guide shaft and the magnetic head. According to the present invention, in which the guide shaft is sufficiently close to the magnetic head, the influence of the clearance can be suppressed. Therefore, vibration of the magnetic head and also the suspension in a direction parallel to a recording media surface of the disk as well as the up-and-down direction can be further reduced.
In a structure using a magnetic head connection arm, a clearance is required between the magnetic head connection arm and the portion of the rotation mechanism for receiving the magnetic head connection arm. When the magnetic head connection arm is not sufficiently rigid, the displacement of the magnetic pole is larger than the clearance due to the influence of the movement of the magnetic head connection arm. In such a case, the positional relationship between the magnetic pole and the laser spot is generally adjusted by pressing the magnetic head connection arm by a stopper or the like. It is preferable to attach the magnetic head so that the magnetic pole precisely maintains a prescribed positional relationship with respect to the laser spot. This will be more strongly demanded in the future since the size of the magnetic pole will be reduced in order to raise the magnetic field generation efficiency and the magnetic force per unit current for higher-speed recording and also in order to reduce the inductance to increase the magnetic field inversion rate for obtaining a higher recording frequency. In consideration of these factors. It is preferable to use a guide shaft for moving the optical pickup housing also as a mechanism for lifting up and lowering the magnetic head, and to locate the guide shaft on substantially the same plane as the magneto-optical disk or on the same side as the magnetic head with respect to the magneto-optical disk.
In a conventional structure, it is common to use a hinge mechanism to raise and lower the magnetic head. The hinge mechanism inherently has a mechanical play, which significantly influences the precision in the positional relationship between the magnetic pole and the laser spot. According to the present invention, the guide shaft for moving the optical pickup housing also acts as the rotation mechanism for lifting up and lowering the magnetic head. Due to such a structure, the play at the hinge need not be considered unlike in the conventional structure, and the precision in the positional relationship is improved. This only leaves the clearance around the guide shaft as a factor to be considered regarding the positional precision.
By locating the guide shaft substantially on the same plane or on the same side as the magnetic head with respect to the magneto-optical disk, the distance between the guide shaft and the magnetic pole of the magnetic head is shortened. This further improves the precision in the positional relationship between the laser spot and the magnetic pole. As described above, the present invention solves the problem of the vibration of a magneto-optical disk, and reduces the number of components and also the production cost by using the guide shaft also as the mechanism for lifting up and lowering the magnetic head.
Thus, the invention described herein makes possible the advantages of providing a magneto-optical disk recording and reproduction device capable of suppressing a transmission of vibration from an actuator which drives an objective lens to a magneto-optical disk, and reducing the amount of displacement between a magnetic field generation region and a laser spot on a magneto-optical disk irradiated with a laser beam during an information recording operation.
These and other advantages of the present invention will become apparent to those skilled in the art upon reading and understanding the following detailed description with reference to the accompanying figures.